1. Field of the Invention
The present invention relates to a data processing apparatus that performs data processing by using a plurality of storage devices.
2. Description of the Related Art
Recently, there is an increase in number of apparatuses using a semiconductor storage device such as a flash memory so-called a solid state drive (SSD), in place of a hard disk (HDD). The SSD is highly resistant to the vibration or shock. On the other hand, the SSD is expensive for a unit of capacity. When a large capacity is needed, an HDD is used. Thus, the usage of a storage device is determined according to characteristics of the storage device.
Further, recently, there has been an apparatus having a function for encrypting user data stored in the storage device, as a security function. For example, an image forming apparatus has a function for protecting data without reduction in speed when storing personal information, such as document image data or an address book, stored by a user in a device via a data processing apparatus that can encrypts/decrypts data.
On such a background, an information processing apparatus having both the SSD and the HDD generally stores a system program or initial data required for activation on the SSD side, and encrypts and stores user data on the HDD side.
When operating under an environment in which security is taken into consideration, data is generally encrypted via an encryption device in an HDD device or connected to an interface unit in the HDD to prevent the reduction in processing speed for encryption.
When the operation of the HDD is interrupted due to a malfunction, it is demanded to be capable of continuing minimum image-formation operation without suspending a system in the image forming apparatus by suspending only the use of the HDD.
For example, Japanese Patent Application Laid-Open No. 2008-148226 discusses an image forming apparatus which enters any of the following modes to reduce the number of accesses to the HDD when it is determined, based on self-diagnosis information of the HDD, that the HDD will soon break down. The modes include HDD degeneration operation modes such as an HDD read-only mode, a mode without using the HDD, an HDD OFF-power mode, and a data collect mode in the case of HDD expansion.
Further, in the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2008-148226, a failure of the HDD is detected and, and when it is detected that the HDD is not available, the apparatus can be operated in the mode without using the HDD.
However, when the image forming apparatus is operating using an encryption device under an environment in which security is taken into consideration, and when the image forming apparatus is activated in the mode without using the HDD, then processing to write temporary data into alternative storage device mounted on the image forming apparatus.
In an image forming apparatus using an SSD as the alternative storage device, data is recorded without encrypting the data passing through the encryption device. Under such a state, by detaching the SSD from the image forming apparatus and reading contents in the SSD, user information such as image data or an address book can be stolen, and the security level of the user information deteriorates.